1. Field of the Invention
The present invention relates to an LED lamp, and particularly to an LED lamp used as an outdoor street lamp.
2. Description of Related Art
LEDs are well known solid state light sources. An LED is a member for transferring electricity to light by using a theory that, if a current is made to flow in a forward direction in a junction comprising two different semiconductors, electrons and cavities are coupled at the junction region to generate a light beam. The LED has an advantage in that it is resistant to shock, and has an almost eternal lifetime under a specific condition; thus, when the LED is used in a lamp, it is intended to be a cost-effective yet high quality replacement for incandescent and fluorescent lamps.
An LED lamp generally requires a plurality of LEDs, and most of the LEDs are driven at the same time, which results in a quick rise in temperature of the lamp. Generally, since the lamps do not have heat dissipation devices with good heat dissipating efficiencies, operation of the lamps has a problem of instability because of the rapid increase of heat. Consequently, the light from the LED lamp often flickers, which degrades the quality of the illumination. Furthermore, the LED lamp is used in a high heat state for a long time and the life time thereof is consequently shortened.
When the LED lamp is used as a street lamp, it is inconvenient to give frequent maintenances to it because of special conditions in respect to the street lamp, for example, location and height of the street lamp and weather condition. Therefore, the LED street lamp needs to be constructed with a reliable heat dissipation capability and robust to withstand severe weather conditions.